If you need complex pages such as running your own Tradeshow with multiple rooms and sessions, you need to use Cvent or similar tool.
Not sure what you mean by Sponsored, but that's probably independent of the registration and management function.
If you need payment, cvent, eventbrite, or others can help you work that out with Finance.
Webinars - depends on your scale and needs. I prefer GTW.
Please see launchpoint.marketo.com for other known integrators.
I suggest listing out your needs more clearly in preparation for an RFP. We did this exercise recently and discovered Marketo did everything we needed using the Tradeshow/Roadshow programs we built. All we really needed were better landing pages. Now, we did have other needs that did require a Marketo partner, but that was not event related in the end.